JP2009230973A - Lighting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an LED lamp increasing light output power and reducing a high harmonic current in input currents. <P>SOLUTION: The number of LEDs 16 lighted by selectively turning on any one of transistors Q1<SB>1</SB>to Q1<SB>N</SB>corresponding to a phase of a supply voltage is controlled corresponding to a change in supply voltage, thereby allowing lighting of at least any one of the LEDs 16 even in a phase section of a relatively low supply voltage to increase the light output power. An input current conducting section is increased and a current conducting angle is not reduced, thereby reducing the high harmonic current in the input currents. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a lighting device that controls lighting of a plurality of LEDs connected in series with each other.

2. Description of the Related Art Conventionally, an illumination device is known in which an LED module in which a plurality of LEDs are connected in series is connected to a power source. In such an illuminating device, a transistor which is a constant current switch means is connected in series to the LED module, and the current is limited to the LED module by this transistor (for example, refer to Patent Document 1).
Japanese Patent Laying-Open No. 2007-96287 (page 6-7, FIG. 1)

  Although the above-described lighting device has an advantage that the number of parts is small, when the number of LEDs connected in series in the LED module is increased, the conduction start voltage of the LED module is increased and the current conduction angle is narrowed. As a result, the harmonic current increases in the input current, and even if the number of LEDs is increased in order to obtain a higher light output, there is a problem that the effect obtained thereby decreases.

  For example, after the AC power supply is rectified by a rectifying element, it is possible to smooth the voltage by inserting a smoothing capacitor. However, even in this case, the conduction angle of the input current is narrowed, and the harmonic current is included in the input current. There is a problem of increasing.

  This invention is made | formed in view of such a point, and it aims at providing the illuminating device which improved the optical output and suppressed the harmonic current in input current.

  The lighting device according to claim 1 includes a plurality of LEDs connected in series to each other; each LED is connected to each other, and one of them is selectively turned on in response to a power supply voltage phase to pass a constant current. A lighting circuit having a plurality of constant current switch means for controlling the number of LEDs to be lit in response to a change in power supply voltage.

  For example, a transistor or the like is used as the constant current switch means.

  Then, the phase of the power supply voltage is relatively low by controlling the number of LEDs to be turned on in response to the change of the power supply voltage by selectively turning on one of the constant current switch means corresponding to the power supply voltage phase. In the section, it is possible to pass a current so that at least one of the LEDs is lit, so that the light output is improved, the current conduction angle is not narrowed, and the harmonic current in the input current is suppressed.

  The lighting device according to claim 2 is the lighting device according to claim 1, wherein the constant current switch means connected to the LED conducting at a phase with a high power supply voltage is connected to the LED conducting at a phase with a low power supply voltage. The constant current flowing through the LED is set larger than the constant current switch means.

  Then, the constant current that flows through the LED by the constant current switch means connected to the LED that conducts at a low phase of the power supply voltage, and the constant current that flows through the LED by the constant current switch means that connects to the LED that conducts at a high phase of the power supply voltage. By setting it larger than the input current, the input current has a stepped shape corresponding to the waveform of the power supply voltage, and the harmonic current in the input current is further suppressed.

  According to the lighting device of claim 1, the number of LEDs to be lit is controlled in response to a change in power supply voltage by selectively turning on one of the constant current switch means corresponding to the power supply voltage phase. This makes it possible to flow a current so that at least one of the LEDs is lit even in a phase interval where the power supply voltage is relatively low, which can improve the light output and the current conduction angle is not narrowed. The harmonic current of can be suppressed.

  According to the illuminating device of claim 2, in addition to the effect of the illuminating device of claim 1, the constant current flowing through the LED by the constant current switch means connected to the LED conducting at a low phase of the power supply voltage is supplied to the power source. By setting the constant current switch means connected to the LED conducting at a high voltage phase to be larger than the constant current flowing through the LED, the input current becomes a step shape corresponding to the waveform of the power supply voltage. Wave current can be further suppressed.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  1 to 5 show a first embodiment, FIG. 1 is a circuit diagram of a lighting device, FIG. 2 is a side view of the lighting device, FIG. 3 is a plan view showing a part of the lighting device, and FIG. FIG. 5 is an explanatory diagram showing the relationship between the power supply voltage of the lighting device and the input current, and FIG. 5 is a timing chart showing the power supply voltage of the device and the ON timing of each constant current switch means.

  In FIG. 1 to FIG. 3, reference numeral 11 denotes a light bulb-shaped LED lamp that is an LED lighting device as a lighting device. The LED lamp 11 includes a light emitting unit 12, a support unit 13 that supports the light emitting unit 12, and light emission. Cover 14 is a glove that covers part 12 and is attached to support part 13.

  The light emitting unit 12 includes an LED board 17 on which a plurality of LEDs 16 are mounted, and a lighting circuit board (not shown) including a lighting circuit 18 that is electrically connected to the LED board 17 and lights the LEDs 16.

The LED 16 includes, for example, a blue LED chip that emits blue light, and a resin portion that covers the blue LED chip. And in this resin part, the fluorescent substance which mainly radiates | emits the yellow light which is a blue complementary color excited by a part of blue light which a blue LED chip | tip emits is mixed, and each LED16 is white-type illumination light. It is configured to obtain. The LEDs 16 are connected in series with each other. In the following description, the number of LEDs 16 is N (N is an integer equal to or greater than 2), and the LEDs 16 ₁ , 16 ₂ ,. _Let's say _N. In the following description, the subscript code corresponds to the LED 16 having the same subscript code, and the subscript code may be omitted.

The LED substrate 17 has LEDs 16 ₁ , 16 ₂ ,..., 16 _N mounted on one main surface, and is fixed to the support portion 13 by screws or the like (not shown).

The lighting circuit 18 is connected to a commercial AC power source e through a noise-cut capacitor C1 and connected to an input terminal of a rectifying element REC, which is a full-wave rectifying element such as a bridge diode, and the output terminal of the rectifying element REC is used for smoothing. Lighting controllers 21 (lighting controllers 21 _{1 to} 21 _N ) corresponding to the number of LEDs 16 (for example, _N ) are sequentially connected via a capacitor C2. Hereinafter, unless otherwise specified, the characteristics of each element of each lighting control unit 21 are all substantially equal.

As shown in FIG. 1, each lighting control unit 21 (lighting control units 21 _{1 to} 21 _N ) has a voltage dividing resistor R1 (resistors R1 _{1 to} R1 _N-1 ) and a resistor R2 (resistors R2 _{1 to} R2 _N ). And a Zener diode ZD1 in the reverse direction for bias setting (Zener diodes ZD1 _{1 to} ZD1 _N ) are connected in parallel to the capacitor C2, and a constant current switch is connected to the connection point between the resistor R2 and the Zener diode ZD1. As a means, the base of an NPN transistor Q1 (transistors Q1 _{1 to} Q1 _N ) is connected. The collector of each transistor Q1 is connected to the cathode side of the corresponding LED 16 (LEDs 16 _{1 to} 16 _N ), and the emitter of the transistor Q1 is a resistor R3 (resistors R3 _{1 to} R3 _N that forms a current limiting means together with the transistor Q1. ) To the anode side of the Zener diode ZD1.

  The Zener diode ZD1 is for setting the base potential of each transistor Q1.

Further, each of the lighting control section 21 ₁ ~21 _N-1 except for the lighting control section 21 _N, switching unit 23 for controlling on and off of the transistors Q1 (switching portion 23 ₁ ~23 _N-1) are connected Yes. Each switching unit 23 (switching units 23 ₁ to 23 _N-1 ) has a Zener diode ZD2 (Zener diode ZD2) in the reverse direction on the cathode side of the forward diodes D1 and D2 respectively connected to the input terminals of the rectifier element REC. _{1 to} ZD2 _N-1 ), a series circuit of a resistor R4 (resistors R4 _{1 to} R4 _N-1 ) and a resistor R5 (resistors R5 _{1 to} R5 _N-1 ) for voltage division are connected, and the resistor R5 is connected to the Zener diode ZD1. Connected to the anode side, the base of an NPN transistor Q2 (Q2 _{1 to} Q2 _N-1 ) as switching means is connected to the connection point of resistors R4 and R5, and the collector of these transistors Q2 is a resistor It is connected to a connection point between R1 and R2, and the emitter of the transistor Q2 is connected between the anode side of the Zener diode ZD1 and the resistor R5.

Zener diode ZD2 is for setting the base potential of the transistors Q2 resistors R4, R5 together with their Zener voltage _{VZ (VZ 1 ~VZ N-1} ) from the Zener diode ZD2 ₁ to Zener diode ZD2 _N-1 For example, in the present embodiment, it is set to increase stepwise (stepwise) with a predetermined constant voltage width. The Zener voltage VZ _m (m is an integer of 1 to N−1) is set to Vf × m <VZ _m ≦ Vf × m−1 with respect to the forward voltage Vf of the LED 16. Further, the Zener voltage VZ _N-1 of the Zener diode ZD2 _N-1 is set to be smaller than the maximum voltage of the commercial AC power source e smoothed by the capacitor C2.

  Further, as shown in FIGS. 2 and 3, the support portion 13 is configured by connecting a base 27 via an insulating member 26 to a heat radiating member 25 that radiates heat generated from the LED 16 or the like.

  The heat radiating member 25 is formed of a member having excellent thermal conductivity such as aluminum. In addition, an insertion hole for inserting a wiring (not shown) that electrically connects the lighting circuit 18 side and the base 27 side is provided inside the heat dissipation member 25.

  The base 27 is electrically connected to a commercial AC power source e (FIG. 1) by being screwed into a socket (not shown).

  The cover 14 has translucency and is fixed by being screwed to the heat radiating member 25.

  Next, the operation of the first embodiment will be described. This operation will be described as an example when the number of LEDs 16 is four (N = 4).

  The LED lamp 11 is supplied with power from a commercial AC power source e with the base 27 screwed into a socket or the like.

  At this time, when the power supply voltage effective value Vr smoothed by the capacitor C2 is not less than 0 and less than Vf, that is, the phase of the commercial AC power supply e is 0 to T1 (T9 to T11, T19 to T20) shown in FIG. Since the voltage Vr applied to the LED 16 is smaller than the forward voltage Vf of the LED 16, no current flows through the LED 16, and all the LEDs 16 do not light up.

Then, the power supply voltage effective value Vr which is smoothed by the capacitor C2 is more than Vf VZ ₁ below states, i.e., T1 to T2 the phase of the commercial AC power source e is shown in FIG. 4 (T8~T9, T11~T12, T18~T19 ), All transistors Q2 are turned off and all transistors Q1 are turned on by reverse blocking of the Zener diode ZD2. At this time, by the voltage Vr (Vf ≦ Vr <2 × Vf) is applied to the LED 16, the transistor Q1 ₁ by LED 16 ₁ only flows constant current the If _1.

Furthermore, in the state where the power supply voltage effective value Vr is VZ ₁ or more and less than VZ ₂ , that is, the phase of the commercial AC power source e is T2 to T3 (T7 to T8, T12 to T13, T17 to T18) shown in FIG. transistor Q2 ₁ a current flows through the Zener diode ZD2 ₁ is turned on, so that only the transistor Q1 ₁ missing base current of the transistor Q1 ₁ is turned off. At this time, when a voltage Vr (2 × Vf ≦ Vr <3 × Vf) is applied to the LED 16, a constant current If ₂ ( ₂ ) is supplied to the two LEDs 16 ₁ and 16 ₂ by the turned-on transistor Q 1 ₂ . = If ₁₎ flows.

Further, in the state where the power supply voltage effective value Vr is VZ ₂ or more and less than VZ ₃ , that is, the phase of the commercial AC power source e is T3 to T4 (T6 to T7, T13 to T14, T16 to T17) shown in FIG. Zener diode ZD2 and _1, ZD2 ₂ current flows transistor Q2 _1, Q2 ₂ is turned on, thus the transistors Q1 _1, Q1 transistor Q1 ₁ base current missing of _2, Q1 ₂ is turned off, respectively. At this time, when a voltage Vr (3 × Vf ≦ Vr <4 × Vf) is applied to the LED 16, a constant current If ₃ ( ₃ ) is supplied to the three LEDs 16 _{1 to} 16 ₃ by the transistor Q1 ₃ that is turned on. = If ₁₎ flows.

When the power supply voltage effective value Vr is VZ ₃ or more and less than VZ ₄ , that is, when the phase of the commercial AC power supply e is T4 to T6 (T14 to T16) shown in FIG. 4, the zener diodes ZD2 _{1 to} ZD2 ₃ current flows transistor Q2 ₁ ~Q2 ₃ is turned on, thus the transistor Q1 ₁ ~Q1 ₃ missing base current of the transistor Q1 ₁ ~Q1 ₃ is is turned off, respectively. At this time, by the voltage Vr (4 × Vf ≦ Vr) is applied to the LED 16, the transistor Q1 _4, all LED 16 ₁ ~ 16 ₄ at a constant current If ₄ (= If ₁₎ flows.

  Therefore, the current (input current I) flowing through the LED 16 becomes constant in the phases T1 to T9 and T11 to T19 of the power supply voltage V as shown in FIG.

Thus, by controlling in accordance with the number of LED16 to light by one it is selectively turned on in the power supply voltage phase corresponding to the transistor Q1 ₁ ~Q1 _N to the power supply voltage changes, the source voltage V Since at least one of the LEDs 16 can be lit even in a relatively low phase interval, the light output can be improved, the conduction interval of the input current I is expanded, and the current conduction angle is not narrowed. Harmonic current inside can be suppressed, and the power factor can be improved.

  In addition, the configuration of the lighting circuit 18 is more complicated than necessary by controlling the on / off timing of the transistor Q1 by the transistor Q2 in which the on / off timing is set according to the power supply voltage phase using the Zener voltage VZ of the Zener diode ZD2. It does not become.

  Next, FIG. 6 shows a second embodiment, and FIG. 6 is an explanatory diagram showing the relationship between the power supply voltage of the lighting device and the input current. In addition, about the structure and effect | action similar to the said 1st Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

The second embodiment has a circuit (FIG. 1) similar to that of the first embodiment, but the current If flowing in the LED 16 (LEDs 16 _{1 to} 16 _N ) is a phase with a high power supply voltage. The transistor Q1 connected to the cathode side of the LED 16 that conducts in the step is set to increase stepwise (stepwise) from the transistor Q1 connected to the cathode side of the LED 16 that conducts at a low phase of the power supply voltage. It is what.

For example, the magnitude of the current If changes the characteristics of the transistor Q1, the Zener voltage of the Zener diode ZD1 (Zener diodes ZD1 _{1 to} ZD1 _N ), the resistor R1 (resistors R1 _{1 to} R1 _N ), or the resistor R2 (resistor R2 ₁ They are respectively set by changing the like resistance of ~R2 _N).

  In the present embodiment, the increase width of the current If from the LED 16 conducting at a high power supply voltage phase to the LED 16 conducting at a low power supply voltage phase is set to be substantially constant. The increase width can be arbitrarily set, for example, the increase width is gradually decreased.

And similarly to the said 1st Embodiment, when LED16 grade | etc., Explains, when the phase of the commercial alternating current power supply e is 0-T1 (T9-T11, T19-T20) shown in FIG. Since the voltage Vr applied to the LED 16 is smaller than the forward voltage Vf of the LED 16, no current flows through the LED 16, all the LEDs 16 do not light up, and the phase of the commercial AC power source e is T1 to T2 shown in FIG. (T8~T9, T11~T12, T18~T19) in the state of oN transistors Q1 ₁ by LED 16 ₁ only flows constant current the If _1. Further, T2 to T3 phase of the commercial AC power source e is shown in FIG. 6 (T7~T8, T12~T13, T17~T18) in the state, the transistor Q2 ₁ which is turned on by current flowing through the Zener diode ZD2 ₁ Only the transistor Q1 ₁ is turned off, and a constant current If ₂ (> If ₁ ) flows through the two LEDs 16 ₁ and 16 _{2 due} to the transistor Q1 ₂ being turned on. Further, when the phase of the commercial AC power source e is T3 to T4 (T6 to T7, T13 to T14, T16 to T17) shown in FIG. 6, the transistor Q2 turned on by current flowing through the Zener diodes ZD2 ₁ and ZD2 ₂ Transistors Q1 ₁ and Q1 ₂ are turned off by ₁ and Q2 ₂ respectively, and a constant current If ₃ (> If ₂ ) flows through the three LEDs 16 _{1 to} 16 ₃ by the transistor Q1 ₃ being turned on. In the state of T4~T6 (T14~T16) showing the phase of the commercial AC power source e is 6, the transistor Q1 ₁ by transistor Q2 ₁ ~Q2 ₃ which is turned on current flows through the Zener diode ZD2 ₁ ~ZD2 ₃ ～Q1 ₃ are turned off, respectively, by transistors Q1 _4, all LED 16 ₁ ~ 16 ₄ constant current If ₄ (> If ₃₎ flows.

  As a result, the same operational effects as those of the first embodiment can be obtained, and a constant current that flows through the LED 16 by the transistor Q1 connected to the LED 16 that conducts at a low phase of the power supply voltage is changed to a phase with a high power supply voltage. By setting the transistor Q1 connected to the LED 16 that is turned on at a larger value than the constant current flowing through the LED 16, the input current I becomes a stepped waveform corresponding to the waveform of the power supply voltage, and the harmonic current in the input current I is Can be suppressed more.

  In each of the above embodiments, the same effect can be obtained even if the transistor Q1 is of the PNP type, for example, and each collector side is connected to the anode side of the LED 16.

  Further, not only the bulb-shaped LED lamp 11 but also various other lighting devices using LEDs can be handled.

  Furthermore, the number of LEDs 16 connected in series can be any number as long as it is two or more.

  The detailed configuration of the lighting circuit 18 is not limited to the above, and the number of LEDs 16 that are turned on by supplying a current by selectively turning on the constant current switch means corresponding to the phase of the power supply voltage V. Any configuration can be used as long as the configuration is variable.

It is a circuit diagram of the illuminating device which shows the 1st Embodiment of this invention. It is a side view of an illuminating device same as the above. It is a top view which shows a part of illumination apparatus same as the above. It is a timing chart which shows the power supply voltage of a lighting apparatus same as the above, and the ON timing of each constant current switch means. It is explanatory drawing which shows the relationship between the power supply voltage and input current of an illuminating device same as the above. It is explanatory drawing which shows the relationship between the power supply voltage and input current of the illuminating device which shows the 2nd Embodiment of this invention.

Explanation of symbols

11 LED lamps as lighting devices
16 LED
18 Lighting circuit
Q1 Transistors as constant current switching means

Claims (2)

A plurality of LEDs connected in series with each other;
A plurality of constant current switches that are connected to each LED and control the number of LEDs that are turned on by supplying a constant current when one of them is selectively turned on according to the power supply voltage phase. A lighting circuit with means;
An illumination device comprising: The constant current switch means connected to the LED that conducts at a phase with a high power supply voltage should have a larger constant current flowing through the LED than the constant current switch means connected to the LED that conducts at a phase with a low power supply voltage. The lighting device according to claim 1.

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